550 NIOHOLLS'S SEAMANSHIP AND NAUTICAL KNOWLEDGE Net Register Tonnage is the residual tonnage after various allowances for propelling power, crew spaces and navigation spaces have been deducted from the gross tonnage. Canal dues are payable on the tonnage stated in the certificates granted by the Panama and Suez Canal Authorities respectively. The assessable tonnage space is based on the Panama and Suez rules which, in some respects, differ from each other and from the British rules, so that all vessels using these Canals must be inspected and measured for these certificates. The Panama Canal net tonnage is based on the ship's actual earning or cargo carrying capacity, and includes all covered in spaces such as forecastle, poop, bridge space, shelter deck or 'tween decks, and this tonnage determines the canal dues to be paid by the ship. The tolls are $1.25 per ton for loaded vessels and $0 75 per ton when in ballast with, in the latter case, a restriction as to the quantity of bunkers that may be allowed in lieu of ballast. The Suez Canal toll is 5/9 per ton for loaded ships and half that amount for vessels in ballast, with a levy for passengers: 5/9 for each adult and 2/10J for each child between 3 and 12 years of age. Additional charges are made by both Canal Authorities for pilotage, towage, etc. MINISTRY OF HEALTH. Port Local Authority.—When a vessel enters a port from overseas she is visited by the boarding Medical Officer of Health, to whom the master gives in the following form a " Declaration of Health." If the ship is healthy the medical officer certifies that he has examined the ship and finds no medical reasons for withholding pratique. The Immigration Officer ascertains, with regard to aliens entering the country, the length of their stay, the purpose of their visit and the amount of money in their possession. No alien is allowed to land who is a lunatic or mentally defective, or suffering from T.B., leprosy, etc., or in a verminous condition. DECLARATION OF HEALTH (To be rendered by the Master of a foreign-going ship arriving in Great Britain or Northern Ireland from a foreign port) THE ATTENTION or THE MASTEB is DniECTED TO THE INSTBUOTIONS XINPEB ARTICLES 5, 6 AND 19* Name of Vessel...............................................,..„...........„.................... From........................................ Via.......................................... Nationality................................ Net Registered Tonnage...................